Tag Archives: PWM

GridVortex talks Atmel on LinkedIn

Jonny Doin, the founder and CEO of GridVortex Systems, recently explained why and how his company uses Atmel microcontrollers (MCUs) in a series of LinkedIn posts.

First off, Doin said he was quite pleased with the support he’s received from global Atmel staff in various locations, including San Jose, France, Spain and Germany.

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“We needed support for the crypto core details for the CPKCL and promptly [kicked-off] a teleconference with the crypto guys in France,” he wrote. “I now try to use Atmel parts in all my projects.”

In terms of specific silicon, Doin said:

“If you need a Cortex-M that does serious crypto operations, consider using an [ARM-powered] SAM4C16 from Atmel. It is a dual Cortex-M4 with 1MB/2MB Flash, 128K/256K RAM and very strong crypto support. The chip is targeted [at] Legal Metrology and offers secure hardware crypto to support TLS/SSL.

“It [also boasts] hardware support for ECC512, RSA1024, independent circuitry for AES and a subsystem that monitors memory areas and generates exception when the hash of the area changes. From what I saw, [this] is the fastest ECC512 engine in a microcontroller, [although it does not] tax the MCU cores. [Yes], you will need a crypto NDA to get access to the crypto hardware documentation, but the ECC crypto API is really complete. The timings are impressive and outperform [other microcontrollers].”

Doin also noted that he is currently testing an Energy Meter that includes an ARM-based SAM4C.

“Atmel has won almost all chips on my design. I am using the SAM4C, ATM90E25, AT86RF212B and the LED controllers from mSilica, MSL20xx. I try to use Atmel parts in all my projects. The IPv6 router for my mesh networking is being designed around the SAMA5D3. The intelligent nodes in the mesh are SAM4C16+AT86RF212B. My software defined LED power driver is being built around the SAMD10/MSL20xx and our intelligent smart vision cameras will also use Atmel processors.”

In addition, Doin confirmed that his company was in the process of designing its endpoint hardware with the SAM4C16.

“The documentation is really good, and so far we just got everything we needed directly from the datasheet,” he added. “Maybe we’ll [also] decide to use a SAM4C32 in one of our designs, so I am looking forward to the updated datasheet.”

Last, but certainly not least, Doin said he successfully designed a high-precision servo-DAC using delta demodulation and one of the center-aligned PWMs of the SAM4C16.

“Using just one digital output and one ADC input I achieved a very stable, precision DAC, at under 19cents of external discrete components. I [recently showcased] the DAC prototype at a recent meeting in Atmel San Jose. I plan to publish the design as an AppNote for the SAM4C16 (and also for the ATmega, which also has the same PWM) and present it as a lecture at the next Embedded Systems Conference,” he concluded.

Interested in learning more about Atmel’s portfolio for your next project? You can check out a detailed breakdown of our microcontrollers here.

Video: An Atmel-powered PID magnetic levitator

A Maker by the name of Davide Gironi recently built an Atmel-powered (Atmega8 MCU) PID magnetic levitator designed to control a small 12V 50N coil using pulse-width-modulation (PWM).

According to the HackADay crew, a hall effect sensor (Allegro A1302) mounted inside the coil is tasked with detecting the distance to the magnet – with the data used by a PID controller to automatically adjust the PWM of the coil to keep the magnet in place. The PID controller parameters, along with other configuration options, are stored in EEPROM and can be edited via software using the UART connection.

“The Atmega8 runs at 8Mhz and the hall effect sensor is polled every 1ms to provide an updated value for the PWM,” explained HackADay’s James Hobson.

“Davide has also thrown in an RGB LED that lights up when an object is being levitated.”

It should be noted that the above-mentioned Atmel-powered PID magnetic levitator was recently showcased by his friend Paolo Crespi at InverART 2013.

Interested in learning more? You can check out the project’s official page here.

Designing an Arduino-powered pneumatic flight simulator

A Maker by the name of Dominick Lee has created an Arduino-powered pneumatic flight simulator dubbed “LifeBeam.”

According to Lee, the LifeBeam Flight Simulator is basically a motion platform capable of performing full rotations tilting at about 40-degrees – an efficient equivalent to the traditional “Stewart Platform” simulator. Indeed, the LifeBeam manages the same physical movements (2DOF), although it only runs on two pneumatic cylinders while the Stewart platform requires 6.

So how does LifeBeam work? As Lee notes, the LifeBeam comprises a “full setup” of equipment that runs simultaneously and collaboratively.

“The data is first sent from the graphics or gaming PC through a custom software program that acquires game data. The game data is scaled and converted into specific coordinates for the roll and pitch (X and Y) axis,” Lee explained.

“The program sends out the final signal which is received by an Arduino Duemilanove (Atmel ATmega168 or ATmega328). The Arduino has a complex program on it that combines the serial commands and parses certain values to calculate a voltage which is then converted into PWM and sent to a low-pass filter which smoothes the PWM into analog voltage. The analog voltage is connected to a pneumatic valve amplifier which controls the pneumatic cylinders to make the platform move accordingly.”

Interested in learning more about Dominick’s Arduino-Pneumatic Flight Simulator? Be sure to check out the official project page on Instructables here.

High voltage edge-lit TV topologies with Atmel

Bits & Pieces has been getting up close and personal with Atmel’s versatile lighting (MCU) portfolio in recent weeks. First, we took a look at the role Atmel MCUs (microcontrollers) have to play in brightening LED ballasts, highlighting the AVR AT90PWM microcontroller which supports the DALI standard and is used to network multiple ballasts to a centralized system for tighter light level control and significant energy savings.

We’ve also talked about how Atmel MCUs are used to light up both fluorescent and HID ballasts, as well as drive television direct backlights. And today we’ll be discussing high voltage edge-lit TV topologies. Specifically, edge-lit configurations use external power supplies and NFETs to allow voltage power supplies to drive a larger number of LEDs (72 LEDs) per string and can sink up 1A (determined by NFET ratings).

“Atmel LED drivers are capable of driving up to 16 parallel strings of LEDs, all while offering fault detection and management of open-circuit and short-circuit LEDs,” an Atmel engineering rep told Bits & Pieces.

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“These devices address the edge-lit and high-brightness LEDs which require higher power while enabling dimming via external pulse width modulation (PWM) signals or analog current control with an internal digital-to-analog converter (DAC).”

In addition, the engineering rep noted that edge-lit topologies are the most popular backlight architectures in current LCD television applications because they are less expensive (requires fewer LEDs) compared to direct-backlight topologies.

“Edge-lit designs are also capable of offering zone (regional) dimming but are limited to larger tiles (coarse zones) and require expensive diffusers which use light guides to distribute light to desired zones,” the engineering rep continued.

“Edge-lit applications require an external DC-to-DC supply to boost the supply up to 250V to allow 72 LEDs per string. Television manufactures also implement LED string phase shift to reduce the overall RMS power requirements and minimize EMI noise by effectively driving one LED string at a time within a frame time period.”

Interested in learning more about high voltage edge-lit TV topologies with Atmel? Be sure to check out our official device breakdown page here.

A closer look at Atmel’s LED drivers

Yesterday, we talked about Atmel microcontrollers (MCUs) being used to produce warm and inviting light without flickering or humming (fluorescent ballast). Today, we’re going to be taking a closer look at Atmel’s family of general illumination LED drivers which are designed to facilitate intelligent system control for multiple LED parallel arrays.

Atmel’s general illumination LED drivers are ideal for a number of applications, including street lighting, tunnel lights, parking garage lights, fluorescent tube replacements, solar/off-grid lighting, mood and architectural lighting, as well as other general lighting applications.

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“With an adaptive power scheme and correlated color temperature (CCT) compensation circuitry, engineers will be well equipped to meet their requirements for power-efficient, high-performance lighting products,” an Atmel engineering rep told Bits & Pieces.

“Lighting OEMs can use white, RGB and white with red LEDs to achieve the desired white gamut and color control, while Atmel LED drivers are capable of setting an LED current to the desired peak and white point. Devices such as Atmel’s MSL2100 can also be used to individually program each string current to its targeted peak.”

Dimming is achieved by PWM or decreasing the LED constant current. Depending on the desired lighting requirements, one to 16 LED strings are employed in solid-state lighting (SSL) applications. Plus, external NFETs enables an application to sink from 350mA to 1A per string, all while supporting high-voltage LED supplies such as 260VDC.

“Atmel’s Adaptive Power Scaling technology results in significant power savings by automatically adjusting the LED supply to the lowest voltage to maintain regulation across all LED strings,” the engineering rep added.

“Atmel LED drivers offer two or three efficiency optimizers for each color power supply. These optimizers minimize power use while maintaining LED current accuracy, allowing up to 16 interconnected devices to automatically negotiate the optimum power supply voltages.”

Lastly, Atmel’s newest LED drivers feature correlated color temperature (CCT) compensation circuitry, making it easier for engineers to precisely maintain a desired CCT over an entire LED lamp temperature range.

Interested in learning more? A detailed list of Atmel’s LED drivers is available here.

A closer look at Atmel’s Peripheral Event System

As previously discussed on Bits & Pieces, Atmel recently introduced the SAM D20 MCU, an extensive product lineup based on ARM’s Cortex -M0+.


The SAM D20 boasts a number of power-saving techniques, including an event system that allows peripherals to communicate directly with each other without involving the CPU or bus resources. This is known as the Peripheral Event System.

According to Andreas Eieland, Sr. Product Marketing Manager at Atmel, the Peripheral Event System can best be described as a routing network independent of the traditional data bus paths. Meaning, different triggers at the peripheral level can result in an event, like a timer tick triggering a reaction in another peripheral.

“Comprising 8 independent channels, the Event System offers a fixed latency of 2 cycles. Without any jitter it is a 100% deterministic method and a perfect fit for real-time applications,” Eieland explained.

“No events are lost and they are handled at a peripheral level in two cycles, even if the CPU is performing a non maskable interrupt. Traditionally the way of handling actions for a low power application would be through the use of interrupts, although they wake up the CPU.”

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To better illustrate the advantages of an Event System, Eieland cited an example of a motor drive application using PWM.

“To detect erroneous situations, many motor applications use an analog comparator or ADC to measure the current going into the motor drive, in an over current situation you want to shut down the PWM channels driving the motor as soon as you can to prevent permanent damage to the circuit and for safety reasons,” he said.

“Without an Event System the overcurrent situation will trigger an interrupt, but the interrupt service request might be delayed if the CPU is performing other higher priority tasks. Using the Event System you can connect the analog comparator or ADC directly to the timer and always shut down the timer in two cycles, regardless of what the rest of the MCU is doing.”

Although Peripheral Event capabilities are useful on many different levels, the primary advantages of such a feature include minimizing power consumption, optimizing the off-loading of routine tasks from the CPU and achieving a totally predictable reaction time.

Additional information about Atmel’s Peripheral Event System can be found here.